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You might have heard about 3D printing. It's where a robotic arm builds a plastic object one layer at a time. It's a pretty amazing technology that has now become controversial. A blogger in Wisconsin and a law student at the University of Texas were able to print part of a gun. The story was widely circulated, sparking fears that people could start printing out unregulated, untraceable guns in their own homes.
Reporter Eric Molinsky went to talk to people in the 3D printing community.
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ERIC MOLINSKY, BYLINE: On the Westside of Manhattan, behind large glass windows, a dozen 3D printers are building plastic toys and jewelry.
Hilary Brosnihan is a manager at 3DEA, an events company that sponsored this pop up store, which is funded by 3D printing companies. Their message to the public is...
HILARY BROSNIHAN: This is coming down the line and it's coming down the line very quickly.
MOLINSKY: Brosnihan also works as a toy manufacturer and 3D printing has been a boon for her business. The idea of printing a gun horrifies her. She thinks that most of her colleagues feel the same way.
BROSNIHAN: They are more of an open source community that's about developing things that are useful. And, in our terms, weapons aren't really useful; creating a way to adjust your sink faucet so you don't have issues with it, that's useful.
MOLINSKY: But a lot of Americans think guns are useful. Matt Griffin is writing a book about 3D printing and he works in the industry. When he visits colleagues outside New York or San Francisco, he definitely sees a cultural difference on guns.
MATT GRIFFIN: All up and down in the Midwest, there's some amazing makers where the idea of, you know, making cars and guns, and all the other sort of cool-for-guys kind of things, it was not separate from, you know, making the cool stuff that I recognize from maker fairs.
MOLINSKY: Now, it would be easy to get the idea that 3D printers are churning out cheap handguns. But that's not even close to being true. If you were to print an entire gun out of plastic, it wouldn't work. The bullet should shatter the plastic.
GRIFFIN: You can print a gun in metal but that kind of technology is not available to hobbyists now, or any time in the near future.
MOLINSKY: Again, Matt Griffin.
GRIFFIN: The primary ways of doing this involve vacating a chamber and flooding it with gases. And you have to keep the gases mixed at this, you know, really careful percentage or it explodes. It doesn't fizzle out and stop working it actually explodes.
MOLINSKY: You can print an important piece of the gun called the lower receiver. It's the central component that connects many of the other parts.
Pete Prodoehl works at a 3D printing shop in Milwaukee.
PETE PRODOEHL: The government considers the lower receiver the gun - like, that's the part with the serial number. That's the part that's regulated.
MOLINSKY: That's how they trace guns. But if someone wanted to build an unregulated gun at home, they could already do it with cheap, off-the-shelf parts. But they usually don't - for good reason.
PRODOEHL: You know, it might fire once and it might not, you know, blow up in your face.
PRODOEHL: But, you know, building something that is reliable and repeatable and somewhat safe for the user, is a little more tricky.
Advocates of 3D printing worry the technology is getting caught up in the national debate over guns. For many of Matt Griffin's colleagues, the issue comes down to personal responsibility - which in a way, mirrors the gun debate itself.
GRIFFIN: I met some folks who were saying: I don't want anybody to tell me I can't make something. So hearing somebody talk about, you know, maybe we need to talk about what people should be allowed to or able to make, they would get extremely upset.
MOLINSKY: But at least one congressman is concerned about where 3D printing is headed. New York Representative Steve Israel is pushing to renew a 1988 law that bans plastic weapons.
For NPR news, I'm Eric Molinsky.